Update: It is indeed as I thought that the PATH environment variable does not match.
Knime: PATH=/usr/bin:/bin:/usr/sbin:/sbin
OS: PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/Library/Apple/usr/bin:/Applications/Wireshark.app/Contents/MacOS
Anyone knows how to adjust this as I could not find anything in the Knime preferences?
Many thanks in advance
Mike